$A$ crane pulls up a car weighing $500 \, kg$ to a vertical height of $4 \, m$. Calculate the work done by the crane. (in $J$)

What are the factors on which the work done depends?

Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?

$A$ body is moving with constant speed over a frictionless surface. What is the work done by the weight of the body?

$A$ person holds a bundle of hay over his head for $30$ minutes and gets tired. Has he done some work or not? Justify your answer.

An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?